1. Field of the Invention
The invention relates to monitoring selected pollutants or moisture in a fluid stream and somewhat more particularly to a method and apparatus for long-term monitoring of pollutant emissions and pollutant immissions as well as moisture content of various fluid streams, such as an air stream, wherein a chemical reaction or absorption between a pollutant or moisture in the fluid stream with a suitably reactive chemical is utilized as the detection principle and is quantitatively analyzed.
2. Prior Art
A method and apparatus for monitoring gaseous pollutants and/or moisture content of a gas wherein a chemical reaction or absorption between a pollutant or moisture in a gas stream with a solid reaction partner is utilized as a detection principle, is known from the Draeger Test Tube Handbook, 4th Edition, May 1979, Special Publication 2340. The operative principle utilized with the test tubes employed (so-called Draeger tubes), is based on the fact that a chemical compound which is specific for a gas or gaseous component to be detected is emplaced in the tube as a permeable filler material and the tube is then charged with a sucked-in gas stream whereby, corresponding to the concentration of the material being detected and the duration of the sample-taking action (sucked-through air or number of pump strokes, respectively), a discolored zone in the filler column or a lengthened zone of the filler column due to material swelling or expansion, develops. The length of the discolored zone or of the zone which is expanded, respectively, is regarded as the measure of pollutant or moisture concentration respectively. With the foregoing method, gases and vapors, such as hydrogen sulfide, sulfur dioxide, carbon disulfide, carbon monoxide, carbon dioxide, alcohol, benzene, hydrocarbons, nitrous gases and water vapors can be detected and at least partially quantitatively analyzed when one of the foregoing materials or components enters into a specific color reaction with a suitable solid chemical. An example of the foregoing is demonstrated by the reaction: EQU H.sub.2 S+Pb.sup.++ .fwdarw.PbS+2H.sup.+.
For determination of hydrogen sulfide (H.sub.2 S), a test tube is filled with a lead-containing preparation as the reagent, which can be applied onto a silic gel carrier and a gas containing H.sub.2 S is charged into the tube so as to come into intimate contact with the reagent therein. With the aid of suitably calibrated standards or preparations, the quantity of hydrogen sulfide converted to lead sulfide (with PbS being equalled to the discolored zone) can then be visually determined. For determining water concentration in air, for example, a similar test tube filled with starch or silica gel as the reagent can be utilized.
In addition to the disadvantages of visual determinations, a further disadvantage of the foregoing technique is that remote measurements and time specifications, limitation circuits, etc., coupled therewith are not possible, without a substantial increase in technical outlay.